Without blood, tissue dies. The goal of this project is to develop very small sensors - looking something like this, -- that can be placed flat on the wall of a blood vessel and measure its blood flow. This new device is called a patch-sensor, and this STTR Phase I is to establish its proof-of-concept by making one and demonstrating that it works in a living animal. The significance of this device is in its potential role in a wide range of surgical procedures. These include, for acute use, monitoring crucial post-operative blood flow in vascular and plastic surgical reconstructions, trauma and general surgery, and for long- term use, monitoring bypass grafts in the leg and heart (using an implant to power the sensor and wirelessly transmit the measurement results). DVX, the small business applying for the STTR, has developed special ultrasound transducers -- diffraction-grating transducers, "DGT's" -- made of PZT piezoceramic that have been successful in measuring blood-flow in artificial vessels, i.e. grafts, when embedded flat in the graft wall. The NIH Resource on Medical Ultrasonic Transducer Technology at USC, the research institution in this project, has learned to fabricate high frequency piezopolymer transducers that are thin, flexible films, ideal for patch sensors. Piezopolymers are not as sensitive as piezoceramics, but their capability for high frequency operation, to utilize the higher scattering of ultrasound at high frequencies, and to be conformal on vessels, so that they pick up more of the scattered signal, compensates for their lower sensitivity. Working together, DVX and USC will design, fabricate, and test in an animal high frequency diffraction-grating transducers of piezopolymer to meet the goal of a blood- flow measuring patch-sensor. Having proved the concept, in Phase II they intend to develop different versions of this technology for particular clinical applications. PUBLIC HEALTH RELEVANCE The goal of this project is developing a simple sensor that can be applied to the side of a blood vessel and provide crucial information about the amount of blood flowing through it. This will improve both post-operative and long-term care for millions of surgical patients a year. [unreadable] [unreadable] [unreadable]